JP2011230500A - Inkjet head and inkjet apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet head capable of preventing ink stagnation while ensuring high ink discharge power.SOLUTION: The inkjet head includes: an ink chamber; an ink supply flow channel through which ink to be supplied to the ink chamber flows; an ink discharge flow channel through which the ink discharged from the ink chamber flows; a partition wall constituting a side surface of the ink chamber; an ink inlet opening, formed in the partition wall and communicating with the ink supply flow channel; a piezo plate constituting a top surface of the ink chamber; a laminated piezoelectric element, which is placed inside the ink chamber and can expand and contract, and which has a fixed end fixed to the piezo plate and has a movable end being the end in the direction of expansion and contraction; a nozzle plate constituting a bottom surface of the ink chamber; and a nozzle, formed in the nozzle plate and communicating with the ink chamber; wherein the laminated piezoelectric element is separated from the partition wall, and the ink inlet opening is positioned closer to the fixed end than to the movable end in the laminated piezoelectric element.

Description

  The present invention relates to an inkjet head and an inkjet apparatus including the inkjet head.

  A drop-on-demand ink jet head is known as an ink jet head that can apply a necessary amount of ink when necessary according to an input signal. In particular, piezoelectric drop-on-demand ink jet heads are being actively developed because they can apply a wide variety of inks with fine control. A piezo-type drop-on-demand ink jet head generally includes an ink supply channel, a plurality of ink chambers connected to the ink supply channel, and a nozzle that applies pressure to the ink filled in the ink chamber. Device.

  In a piezo-type inkjet head, pressure is applied to ink in an ink chamber due to mechanical distortion of the piezo element caused by applying a drive voltage to the piezo element, and ink droplets are ejected from nozzles. Piezo-type inkjet heads can be broadly classified into three types: a shear mode type, a push mode type, and a bend mode type, depending on how the piezoelectric elements are distorted. In particular, the bend mode type inkjet head using a piezo element having a laminated structure can generate a strong force at a low voltage, and therefore is expected to be developed for the manufacture of electronic devices such as organic EL displays and liquid crystal panels that use high-viscosity inks. (For example, refer to Patent Document 1).

  In addition, air may be mixed into the ink in the ink chamber or the nozzles may be clogged, making it impossible to discharge ink appropriately. In view of this, there has been proposed a technique for reducing air mixing and nozzle clogging by circulating ink in an inkjet head (supplying ink to an ink chamber and discharging ink from the ink chamber) (for example, Patent Documents 2 and 2). 6).

  Further, an ink circulation type ink jet head in which a piezo element is disposed in an ink chamber has been proposed (see, for example, Patent Documents 7 and 8).

  FIG. 1 is a cross-sectional view of an ink circulation type ink jet head described in Patent Documents 7 and 8. FIG. As shown in FIG. 1, the inkjet head 1 described in Patent Documents 7 and 8 is discharged from an ink chamber 10, an ink supply channel 11 through which ink to be supplied to the ink chamber 10 flows, and the ink chamber 10. And an ink discharge channel 12 through which the discharged ink flows.

  The ink chamber 10 constitutes the bottom surface of the ink chamber 10, the nozzle plate 20 on which the nozzles 21 are formed, the top surface of the ink chamber 10, the piezo plate 30 to which the piezo elements 31 are fixed, and the ink chamber 10. It is comprised from the partition 40 which comprises the side surface of this.

  The piezo plate 30 has an ink inlet hole 33 for supplying ink from the ink supply channel 11 to the ink chamber 10 and an ink outlet hole 35 for discharging ink from the ink chamber 10 to the ink discharge channel 12. Is formed.

  Ink flows from the ink supply channel 11 through the ink chamber 10 to the ink discharge channel 12. Therefore, new ink is always supplied into the ink chamber 10. By always supplying new ink into the ink chamber 10, it is possible to prevent ink ejection failure due to stagnation of ink in the ink chamber 10 or air mixing.

  When a drive voltage is applied to the piezo element of the inkjet head 1 having such a structure, the volume of the piezo element 31 expands, and a force in the ejection direction is applied to the ink in the ink chamber 10. The ink to which the force in the ejection direction is applied is ejected from the nozzle 21.

  In such a circulation type ink jet head, stagnation of ink in the ink chamber and air mixing can be eliminated, but there are two escape paths for the force generated by driving the piezo element (ink inlet hole 33 and ink outlet hole 35). Therefore, it has been said that the ink ejection force does not increase.

JP 2000-177121 A JP 2008-200902 A JP 2005-119287 A US Patent Application Publication No. 2005/0093931 JP 2008-087288 A US Patent Application Publication No. 2008/0079759 JP 2009-160807 A US Patent Application Publication No. 2009/0174735

  However, even in a circulation type ink jet head in which ink flows in the ink chamber, the ink stays and may stagnate.

  FIG. 2 is a cross-sectional view of another circulation type ink jet head 2. The inkjet head 2 shown in FIG. 2 has an ink chamber 10, an ink supply channel 11, and an ink discharge channel 12. The ink chamber 10 includes a nozzle plate 20 in which nozzles 21 are formed, a piezo plate 30 to which a laminated piezo element 31 is fixed, and a partition wall 40 that forms the side surface of the ink chamber 10. The partition wall 40 has an ink inlet hole 33 for supplying ink from the ink supply channel 11 to the ink chamber 10, and an ink outlet hole 35 for discharging ink from the ink chamber 10 to the ink discharge channel 12. Is formed. In the inkjet head 2, the laminated piezo element 31 is separated from the partition wall 40. For this reason, a gap is formed between the laminated piezoelectric element 31 and the partition 40.

  As shown in FIG. 2, even if ink is allowed to flow into the ink chamber 10, the ink that has entered the gap between the laminated piezoelectric element 31 and the partition wall 40 is difficult to flow. For this reason, the ink that has entered the gap may remain between the laminated piezoelectric element 31 and the partition wall 40 and may be stagnated. Stagnation of ink in the ink chamber adversely affects ink ejection, such as unstable ink ejection.

  In order to prevent the stagnation of the ink that has entered between the laminated piezo element 31 and the partition wall 40 as described above, an ink inlet hole is formed in the piezo plate 30 instead of the partition wall as disclosed in Patent Document 2. Is also possible. If the ink inlet hole is formed in the piezo plate 30 as in the inkjet head 1 of Patent Document 2 shown in FIG. 1, the ink supplied from the ink inlet hole passes between the piezo element 31 and the partition wall 40. Since it flows, the ink between the piezo element and the partition 40 does not stay.

  However, when the ink inlet hole is formed in the piezo plate 30, a part of the force generated by driving the piezo element escapes through the ink inlet hole, and the ink ejection force decreases (see FIG. 6A).

  SUMMARY OF THE INVENTION An object of the present invention is to provide a circulation type ink jet head that can achieve both elimination of ink stagnation in an ink chamber and strong ejection force.

  The present inventor has found out that the stagnation of the ink in the ink chamber and the strong ejection force can be achieved at the same time by devising the positional relationship between the ink inlet hole and the laminated piezo element. Was completed.

That is, the first of the present invention relates to the following inkjet head.
[1] An ink chamber, an ink supply channel through which ink to be supplied to the ink chamber flows, an ink discharge channel through which the ink discharged from the ink chamber flows, and a partition that forms a side surface of the ink chamber An ink inlet hole formed in the partition wall and in communication with the ink supply channel; an ink outlet hole formed in the partition wall and in communication with the ink discharge channel; and a top surface of the ink chamber A laminated piezo element which is disposed in the ink chamber and is extendable and contractible, and has a fixed end fixed to the piezo plate and a movable end which is an end in the extendable direction. An ink jet head comprising: a nozzle plate that forms a bottom surface of the ink chamber; and a nozzle that is formed in the nozzle plate and communicates with the ink chamber. Ezo element is spaced apart from the partition wall, the ink inlet hole is located at the fixed end side of the movable end of the laminated piezoelectric element, an ink jet head.
[2] The inkjet head according to [1], further including an ink inlet channel that connects the ink inlet hole and the ink supply channel, and the ink inlet channel has a bending point.
[3] The ink jet head according to [1] or [2], further including an ink outlet channel connecting the ink outlet hole and the ink discharge channel, wherein the ink outlet channel has a bending point.

A second aspect of the present invention relates to the following ink jet apparatus.
[4] An ink jet apparatus comprising the ink jet head according to any one of [1] to [3].

  In the ink jet head of the present invention, ink does not stay in the ink chamber and the ink ejection force is strong. For this reason, the inkjet head of this invention can discharge a highly viscous ink stably.

Sectional view showing an example of a conventional inkjet head Sectional drawing which shows the other example of the conventional inkjet head 1 is a perspective view of an inkjet head according to a first embodiment. Sectional drawing by the A line of the inkjet head shown by FIG. Sectional drawing by the B line of the inkjet head shown by FIG. Sectional drawing by the C line of the inkjet head shown by FIG. Enlarged sectional view of the ink chamber shown in FIG. 4A Explanatory drawing of the ink chamber shown in FIG. 4B Enlarged sectional view of the ink chamber shown in FIG. 4A Explanatory drawing of the ink chamber shown in FIG. 4B Cross-sectional view of an inkjet head having an ink inlet hole on the top surface of the ink chamber Cross-sectional view of an ink jet head having an ink inlet hole in a nozzle plate side portion on the side of the ink chamber Sectional drawing of the inkjet head of Embodiment 2. FIG. Sectional drawing of the inkjet head of Embodiment 3 Sectional drawing of the inkjet head of Embodiment 4. FIG. Partial enlarged plan view of the inkjet head shown in FIG. 9A Sectional drawing of the inkjet head of Embodiment 5 Partial enlarged plan view of the inkjet head shown in FIG. 10A Partial enlarged plan view of an inkjet head according to a sixth embodiment

1. About the inkjet head of the present invention The inkjet head of the present invention is a bend mode inkjet head using a laminated piezoelectric element. In addition, the present invention is an ink circulation type inkjet head in which ink flows in an ink chamber.

  The ink jet head of the present invention has 1) an ink supply channel, 2) an ink discharge channel, and 3) an ink chamber. Each component will be described below.

1) Ink supply channel The ink supply channel is a channel through which ink supplied to the ink chamber flows. The ink supply channel has an introduction port through which ink is supplied from the outside. A plurality of ink chambers are connected to the ink supply channel along the ink flow. The ink supply amount supplied to the ink supply channel is not particularly limited, and may be several ml / min or more.

2) Ink discharge channel The ink discharge channel is a channel through which the ink discharged from the ink chamber flows. The ink discharge channel has a discharge port for discharging ink to the outside. A plurality of ink chambers are connected to the ink discharge channel along the ink flow.

3) Ink chamber The ink chamber is a space for containing ink to be ejected from nozzles described later. The ink chamber is connected to the ink supply channel and the ink discharge channel. Accordingly, the ink flows from the ink supply channel to the ink discharge channel through the ink chamber. As a result, new ink is always supplied into the ink chamber. By always supplying new ink into the ink chamber, it is possible to prevent ink ejection failure due to ink stagnation or air mixing in the ink chamber. The flow rate of ink flowing in the ink chamber is preferably 10 to 100 ml / min.

  The maximum number of ink chambers connected to one ink supply channel and ink discharge channel is normally 1024. The type of ink stored in the ink chamber is not particularly limited, and is appropriately selected depending on the type of product. For example, when the product is an organic EL panel, an example of ink stored in the ink chamber includes a solution containing an organic light emitting substance such as a light emitting material. In the case of manufacturing a liquid crystal panel, examples of ink include a high-viscosity functional liquid such as a liquid crystal material.

  Next, members constituting the ink chamber will be described. In the present invention, the ink chamber includes a nozzle plate, a partition wall, and a piezo plate. Therefore, the ink jet head of the present invention further includes 4) a nozzle plate, 5) a partition, and 6) a piezo plate.

4) Nozzle plate The nozzle plate is a plate constituting the bottom surface of the ink chamber. The nozzle plate is, for example, a stainless steel (for example, SUS304 stainless steel) plate having a thickness of 10 to 100 μm.

  Furthermore, the ink jet head of the present invention has a nozzle formed on a nozzle plate. The nozzle is a tube having an ejection hole for ejecting ink from the ink chamber. The ink jet head may have one nozzle for one ink chamber, or may have two or more nozzles. The ink in the ink chamber passes through the inside of the nozzle and is discharged to the outside from the discharge hole. The diameter of the discharge hole is not particularly limited, and may be about 10 to 100 μm, for example.

5) Partition Wall The partition wall is a plate constituting the side surface of the ink chamber. The partition may be manufactured, for example, by bonding a plurality of stainless steel (for example, SUS304 stainless steel) plates by thermal diffusion bonding. The cross-sectional shape of the partition wall may be rectangular or tapered. The height of the partition wall may be 5 to 100 μm higher than the height of the laminated piezoelectric element, and is usually 105 to 1100 μm. The partition walls are attached to the piezo plate and the nozzle plate. The partition wall may be attached to the piezo plate and the nozzle plate by an adhesive or may be attached by welding, or may be attached by thermal diffusion bonding (thermocompression bonding).

  Furthermore, the ink jet head of the present invention has an ink inlet hole and an ink outlet hole formed in the partition wall.

  The ink inlet hole is a hole communicating with the ink supply channel. Therefore, the ink flows from the ink supply channel through the ink inlet hole into the ink chamber. The ink inlet hole and the ink supply channel are usually connected by an ink inlet channel. The ink inlet channel may be linear, but preferably has a bending point (see Embodiment 2, FIG. 7).

  The ink outlet hole is a hole communicating with the ink discharge channel. Therefore, the ink flows from the ink chamber through the ink outlet hole into the ink discharge channel. The ink outlet hole and the ink discharge channel are usually connected by an ink outlet channel. The ink outlet channel may be linear, but preferably has a bending point (see Embodiment 2, FIG. 7).

6) Piezo plate The piezo plate is a plate constituting the top surface of the ink chamber. Here, “the top surface of the ink chamber” means a surface facing the nozzle plate. The material of the piezo plate is ceramics, for example. By using ceramics as the material of the piezo plate, the thermal expansion coefficient of the piezo element and the piezo plate described later can be made the same.

  Furthermore, the ink jet head of the present invention has a piezo element fixed to a piezo plate.

  Piezo elements are actuating devices that convert control signals into actual motion. By applying a driving voltage to the piezo element, the piezo element expands and contracts, and pressure is applied to the ink in the ink chamber. Thereby, ink is discharged from the discharge hole of the nozzle.

  The piezo element in the present invention is a stackable piezo element that can be expanded and contracted (hereinafter also simply referred to as “laminated piezo element”). A laminated piezo element has a slow output response to an input, but has a large output. Therefore, the laminated piezoelectric element can generate a strong force. The height (length in the stacking direction) of the stacked piezoelectric element is usually 100 to 1000 μm.

  The laminated piezo element has a fixed end that is disposed in the ink chamber and is fixed to a piezo plate, which will be described later, and a movable end that is an end in the expansion / contraction direction of the laminated piezo element.

  In the present invention, the laminated piezo element and the above-described partition are separated from each other. For this reason, a gap is formed between the laminated piezoelectric element and the partition. The width of the gap between the laminated piezo element and the partition wall is preferably 5 to 100 μm, and more preferably 5 to 20 μm. If the width of the gap between the laminated piezo element and the partition is 5 μm or less, the laminated piezo element may come into contact with the partition when the laminated piezo element expands due to application of a voltage. On the other hand, when the width of the gap between the laminated piezo element and the partition wall is 20 μm or more, when pressure is applied to the ink, the ink escapes into the gap between the laminated piezo element and the partition wall, and sufficient pressure is applied to the ink. May not be added.

  As described above, the laminated piezoelectric element has a large output, but the generated vibration is also large. For this reason, the vibration of the laminated piezoelectric element may be transmitted to the adjacent ink chamber via the partition wall. Thus, the fact that the vibration of the piezo element in one ink chamber affects other ink chambers is called crosstalk. When crosstalk occurs, the amount of ink droplets ejected between ink chambers becomes unstable, and the ink ejection pitch becomes unstable.

  However, in the present invention, since the laminated piezo element and the partition are separated from each other, the vibration of the laminated piezo element is not transmitted to the adjacent ink chamber through the partition. For this reason, according to the present invention, crosstalk between the ink chambers is reduced.

  The present invention is characterized in that both the elimination of stagnation in the ink chamber and the strong ejection force are achieved by devising the positional relationship between the ink inlet hole and the laminated piezo element. More specifically, according to the present invention, the ink inlet hole is disposed on the fixed end side with respect to the movable end of the laminated piezo element, and as described above, the ink inlet hole is formed in the partition wall. It is characterized by resolving stagnation and strong discharge force.

  Here, “the ink inlet hole is arranged on the fixed end side with respect to the movable end of the laminated piezo element” means that the distance between the movable end and the fixed end of the laminated piezo element that is not driven (the laminated piezo element's It means that the distance between the ink inlet hole and the piezo plate is smaller than the height). The distance between the ink inlet hole and the piezoelectric plate is preferably 100 μm or less, and more preferably 0 (see FIG. 4B). If the distance between the ink inlet hole and the piezo plate is 100 μm or more, the ink between the laminated piezo element and the partition may stay and stagnate. The distance between the movable end of the laminated piezo element and the ink inlet hole along the expansion / contraction direction of the laminated piezo element (hereinafter also simply referred to as “distance between the movable end of the laminated piezo element and the ink inlet hole”) is 100 μm or more. The thickness is preferably 300 μm or more (see FIG. 4B). When the distance between the movable end of the laminated piezo element and the ink inlet hole is less than 100 μm, ink stays between the laminated piezo element and the partition wall, or the force generated by driving the laminated piezo element is applied to the ink inlet hole. It becomes easy to escape.

  In this way, by arranging the ink inlet hole on the fixed end side with respect to the movable end of the laminated piezo element, it is possible to prevent the ink that has entered between the laminated piezo element and the partition from staying (FIG. 5A). reference).

  Furthermore, in the present invention, the ink inlet hole disposed on the fixed end side with respect to the movable end of the laminated piezoelectric element is formed in the partition wall (side surface of the ink chamber) as described above. As described above, the ink inlet hole is formed at the fixed end side with respect to the movable end of the laminated piezo element and on the partition wall, thereby preventing the force generated by driving the laminated piezo element from escaping to the ink inlet hole. (See FIG. 5B). By preventing the force generated by driving the laminated piezo element from escaping to the ink inlet hole, the force generated by driving the laminated piezo element can be efficiently converted into the ink ejection force, and strong ink ejection Power is obtained.

  As described above, according to the present invention, it is possible to achieve both elimination of stagnation in the ink chamber and strong ejection force. For this reason, the inkjet head of this invention can discharge a highly viscous ink stably.

  The effect of the present invention will be described in detail in the first embodiment.

2. About the manufacturing method of the inkjet head of this invention The inkjet head of this invention mentioned above is manufactured by arbitrary methods, unless the effect of this invention is impaired. Preferred examples of the method of manufacturing an inkjet head according to the present invention include 1) a first step of preparing a piezo plate, 2) a second step of laminating a frame on the piezo plate, and 3) a partition wall connected to the frame. And a third step of laminating the nozzle plates.

  1) In the first step, a piezo plate to which a plurality of laminated piezo elements are fixed is prepared. A plurality of laminated piezo elements: i) First, a plurality of sheets of lead zirconate titanate (PZT) and a conductive film are laminated on a piezo plate to produce a driver, and ii) and the driver is divided. It may be produced by. In order to divide the drive body, a dicing apparatus incorporating a rotating blade may be used.

  2) In the second step, a frame is stacked on the piezo plate. Here, the “frame” is a member constituting the side surface of the inkjet head (see FIGS. 3, 4A to C, reference numeral 160). The frame may be affixed to the piezo plate with an adhesive or may be affixed by welding, but may be affixed by thermal diffusion bonding (thermocompression bonding).

  3) In the third step, a nozzle plate to which a plurality of partition walls are connected is laminated on the frame. Thus, an ink chamber having a bottom surface, a side surface, and a top surface is configured.

  The partition walls are arranged so as to be inserted between the laminated piezo elements. The partition wall may be affixed to the nozzle plate with an adhesive or may be affixed by welding, or may be affixed by thermal diffusion bonding (thermocompression bonding). The nozzle plate may be attached to the frame with an adhesive or may be attached by welding, but may be attached by thermal diffusion bonding (thermocompression bonding).

3. About the inkjet device of the present invention The inkjet device of the present invention is characterized by comprising the above-described inkjet head, but otherwise has members of known inkjet devices as appropriate. For example, the ink jet apparatus of the present invention includes a member for fixing an ink jet head, a moving stage for placing and moving an object to which ink is applied, and the like.

  The ink jet apparatus includes an ink circulation device. The ink circulation device circulates ink by supplying a driving pressure to the ink. A pump may be used to supply the driving pressure to the ink, but it is preferable to use a regulator that supplies pressure using compressed air. This is because the use of the regulator makes the driving pressure constant and stabilizes the ink circulation speed.

  The ink jet apparatus may continuously circulate ink of the ink jet head during the operation of the apparatus or may circulate it intermittently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

(Embodiment 1)
FIG. 3 is a perspective view of the inkjet head 100 according to the first embodiment of the present invention. As shown in FIG. 3, the inkjet head 100 includes an ink supply channel 101, an ink discharge channel 102, and an ink chamber 110.

  The ink supply channel 101 has an ink introduction port 103. Further, the ink discharge channel 102 has an ink discharge port 104.

  4A is a cross-sectional view taken along line A of the inkjet head 100 shown in FIG. FIG. 4B is a cross-sectional view taken along line B of the inkjet head 100 shown in FIG. FIG. 4C is a cross-sectional view taken along line C of the inkjet head 100 shown in FIG.

  As shown in FIGS. 4A to 4C, the inkjet head 100 includes a nozzle 111 having a discharge hole 112, a laminated piezo element 113, an ink inlet hole 121, an ink inlet channel 123, an ink outlet hole 125, and an ink outlet channel. 127.

  In addition, the inkjet head 100 has a nozzle 111 formed thereon, a nozzle plate 130 that constitutes the bottom surface of the ink chamber 110, and a laminated piezo element 113 that are fixed, a piezo plate 140 that constitutes the top surface of the ink chamber 110, an ink inlet hole 121, and An ink outlet hole 125 is formed and has a partition wall 150 constituting the side surface of the ink chamber 110. Further, the side surface of the ink jet is constituted by a frame 160.

  The ink chamber 110 is connected to the ink supply channel 101 via the ink inlet hole 121 and the ink inlet channel 123. The ink chamber 110 is connected to the ink discharge channel 102 via the ink outlet hole 125 and the ink outlet channel 127.

  In the present embodiment, the ink inlet channel 123 and the ink outlet channel 127 do not have a bending point and are linear.

  As shown in FIG. 4A, the laminated piezoelectric element 113 is not in contact with the partition wall 150. The gap between the laminated piezo element 113 and the partition 150 is 5 to 100 μm. The laminated piezo element 113 has a fixed end 113a fixed to the piezo plate 140, and a movable end 113b that is an end in the expansion / contraction direction of the piezo.

  As shown in FIG. 4B, the ink inlet hole 121 and the ink outlet hole 125 are formed in the partition wall 150. Further, the partition wall 150 in which the ink inlet hole 121 is formed faces the partition wall 150 in which the ink outlet hole 125 is formed.

  The ink inlet hole 121 is disposed closer to the fixed end 113 a than the movable end 113 b of the laminated piezo element 113. In the present embodiment, the interval between the ink inlet hole 121 and the piezo plate 140 is zero. Further, the distance D between the movable end 113b of the laminated piezo element 113 shown in FIG. 4B and the ink inlet hole 121 along the expansion / contraction direction of the laminated piezo element 113 is preferably 100 μm or more, more preferably 300 μm or more. It is more preferable. On the other hand, the ink outlet hole 125 is disposed closer to the nozzle plate 130 than the movable end 113 b of the laminated piezo element 113.

  Next, the operation of the inkjet head 100 according to the first embodiment will be described with reference to FIGS. 5A to 5D. 5A and 5C are enlarged sectional views of the ink chamber 110 shown in FIG. 4A, and FIGS. 5B and 5D are explanatory diagrams of the ink chamber 110 shown in FIG. 4B.

  First, ink is supplied from the ink tank 105 to the ink supply channel 101. The ink tank 105 preferably has a pressure adjustment mechanism. Since the ink tank has a pressure adjustment mechanism, the ink in the ink tank is consumed and the ink is supplied from the ink tank to the ink supply channel 101 at a constant pressure even when the ink liquid level in the ink tank drops. Can do. The pressure adjusting mechanism may make the pressure of the supplied ink constant by adjusting the height of the ink tank and making the height of the ink liquid surface constant.

  The ink supplied to the ink supply channel 101 is supplied to each ink chamber 110 through the ink inlet channel 123 and the ink inlet hole 121 (see FIGS. 5A and 5B). The ink supplied to the ink chamber 110 is further discharged to the ink discharge channel 102 through the ink outlet hole 125 and the ink outlet channel 127. For this reason, ink flows in the ink chamber 110. As a result, new ink is always supplied into the ink chamber 110.

  Further, as described above, the ink inlet hole 121 is disposed closer to the fixed end 113 a than the movable end 113 b of the laminated piezoelectric element 113. For this reason, ink is also supplied to the space between the laminated piezo element 113 and the partition wall 150, and ink flows in the space between the laminated piezo element 113 and the partition wall 150. Thereby, it is possible to prevent the ink between the laminated piezo element 113 and the partition wall 150 from stagnation.

  On the other hand, as shown in FIG. 2, if the ink inlet hole 33 is disposed on the nozzle plate 20 side with respect to the movable end of the laminated piezo element 31, the ink is formed in the space between the laminated piezo element 31 and the partition wall 40. May stay and the ink between the laminated piezoelectric element 31 and the partition 40 may be stagnated.

  Next, a driving voltage is applied to the laminated piezo element 113. Thereby, the height of the laminated piezo element 113 is increased, and the capacity of the ink chamber 110 is reduced (FIGS. 5C and 5D).

  As described above, in the present embodiment, the laminated piezo element 113 and the partition 150 are separated from each other. Therefore, as shown in FIGS. 5C and 5D, the vibration of the laminated piezo element 113 is not transmitted to the partition 150 even when the height of the laminated piezo element 113 is increased. Thereby, crosstalk between the ink chambers 110 can be reduced.

  Further, as the height of the laminated piezoelectric element 113 increases, a force F1 in the same direction as the ink ejection direction X is generated. As a result, the ink in the ink chamber 110 is ejected by the force generated by driving the laminated piezo element 113.

  Further, a part of the force generated by driving the laminated piezo element 113 is bounced back to the nozzle plate 130 or bounced back to the partition wall 150, so that the force F2 perpendicular to the discharge direction X and the discharge direction X Is converted to a force F3 in the opposite direction.

  In the present invention, since the ink inlet hole 121 is formed in the partition wall 150 and is disposed closer to the fixed end 113a than the movable end 113b of the laminated piezoelectric element 113, the direction of the force F3 that is opposite to the ejection direction X The ink inlet hole 121 does not exist on the extension of. Therefore, the force F3 is difficult to escape to the ink inlet hole 121. For this reason, the force generated by driving the laminated piezo element 113 is efficiently converted into the ejection force.

  On the other hand, when the ink inlet hole 121 is provided not on the side surface of the ink chamber 110 but on the top surface (piezo plate 140) of the ink chamber as shown in FIG. 6A, the force F3 in the reverse direction to the ejection direction X is Easily escape to the hole 121. For this reason, the force generated by driving the laminated piezo element 113 is not efficiently converted into the ink ejection force, and the ink ejection force is reduced.

  Further, even when the ink inlet hole 121 is formed in the partition wall 150, as shown in FIG. 6B, when the ink inlet hole 121 is disposed closer to the nozzle plate 130 than the movable end 113b of the laminated piezoelectric element 113, A force F <b> 2 perpendicular to the ejection direction X tends to escape to the ink inlet hole 121. For this reason, the force generated by driving the laminated piezo element 113 is not efficiently converted into the ink ejection force, and the ink ejection force is reduced.

  Further, in order to prevent the force F2 perpendicular to the ejection direction X from escaping to the ink outlet hole 125, the ink outlet hole 125 may be disposed on the piezoelectric plate 140 side with respect to the movable end 113b of the laminated piezoelectric element 113. Conceivable. However, when the ink outlet hole 125 is arranged on the piezo plate 140 side with respect to the movable end 113b of the laminated piezo element 113, the ink leaks unintentionally from the nozzle 111 when the ink is circulated in the ink chamber 110. This is not preferable because there is a risk of being lost.

  Thereafter, when a voltage opposite to the drive voltage is applied to the laminated piezo element 113, the height of the laminated piezo element decreases and the capacity of the ink chamber 110 increases. As a result, the ink flows again from the ink supply channel 101 into the ink chamber 110.

  As described above, according to the ink jet head of the present embodiment, it is possible to achieve both elimination of stagnation in the ink chamber and strong ejection force.

(Embodiment 2)
In the first embodiment, the ink inlet channel and the ink outlet channel have been described as being linear. In the second embodiment, an embodiment in which the ink inlet channel and the ink outlet channel have bending points will be described.

  FIG. 7 is a cross-sectional view of the inkjet head 200 according to the second embodiment. The inkjet head 200 is the same as the inkjet head 100 of Embodiment 1 shown in FIG. 4B except that the ink inlet channel and the ink outlet channel have bending points. The same components as those of the ink jet head 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 7, in the ink jet head 200 of the present embodiment, the ink inlet channel 223 and the ink outlet channel 227 have a bending point C. Thereby, the pressure loss of the ink inlet channel 223 and the ink outlet channel 227 increases. Therefore, the force F2 perpendicular to the ejection direction X among the forces generated by driving the laminated piezo element 113 is less likely to escape to both the ink inlet hole 121 and the ink outlet hole 125.

  For this reason, according to the present embodiment, the ink ejection force can be further improved.

(Embodiment 3)
In the first embodiment, the mode in which the side surface (partition wall) of the ink chamber is perpendicular to the top surface (piezo plate) and the bottom surface (nozzle plate) has been described. In Embodiment 3, a mode in which a tapered portion is provided on the side surface of the ink chamber will be described.

  FIG. 8 is a cross-sectional view of the inkjet head 300 according to the third embodiment. The inkjet head 300 is the same as the inkjet head 100 of Embodiment 1 shown in FIG. 4B, except that a tapered portion is provided on the side surface of the ink chamber. The same components as those of the ink jet head 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8, in the ink jet head 300 of the present embodiment, a tapered portion 310 is provided on the side surface of the ink chamber 110. More specifically, the tapered portion 310 is provided on the partition wall 150 facing the partition wall 150 provided with the ink inlet holes 121. By doing so, ink and bubbles are less likely to stay in the gap between the piezoelectric element 113 and the partition wall 150. Therefore, according to the present embodiment, the ink ejection force can be further improved.

(Embodiment 4)
In the fourth embodiment, a mode in which a convex portion is provided on the side surface of the ink chamber will be described.

  FIG. 9A is a cross-sectional view of the inkjet head 400 according to the fourth embodiment. FIG. 9B is a partially enlarged plan view of the inkjet head 400 according to the fourth embodiment. FIG. 9B shows a state where the piezo plate 140 is removed. The ink-jet head 400 is the same as the ink-jet head 100 of Embodiment 1 shown in FIGS. 4B and 4C except that a convex portion is provided on the side surface of the ink chamber. The same components as those of the ink jet head 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 9A and 9B, in the inkjet head 400 of the present embodiment, a convex portion 410 is provided on the side surface of the ink chamber 110. The convex portion 410 is provided on the partition wall 150 so as to surround the periphery of the piezo element 113. The ink supplied from the ink inlet hole 121 flows into the lower portion of the ink chamber 110 through the gap between the piezo element 113 and the convex portion 410. By doing so, ink and bubbles are less likely to stay in a specific area in the ink chamber 110. Therefore, according to the present embodiment, the ink ejection force can be further improved.

(Embodiment 5)
In the first embodiment, the configuration in which the width of the ink inlet hole is narrower than the width of the ink chamber has been described. In the fifth embodiment, a mode in which the width of the ink inlet hole is the same as the width of the ink chamber will be described.

  FIG. 10A is a cross-sectional view of the inkjet head 500 of the fifth embodiment. FIG. 10B is a partially enlarged plan view of the inkjet head 500 according to the fifth embodiment. FIG. 10B shows a state where the piezo plate 140 is removed. The inkjet head 500 is the same as the inkjet head 100 of Embodiment 1 shown in FIGS. 4B and 4C except that the width of the ink inlet channel 523 is gradually increased. The same components as those of the ink jet head 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 10A and 10B, in the inkjet head 500 of the present embodiment, the width of the ink inlet channel 523 is gradually increased, and the width of the ink inlet hole 521 is the same as that of the ink chamber 110. It has become. By doing so, ink and bubbles are less likely to stay around the ink inlet hole 521. Therefore, according to the present embodiment, the ink ejection force can be further improved.

  Note that the width of the inlet portion of the ink inlet channel 523 (the connection portion with the ink supply channel 101) is narrower than that of the ink inlet hole 521. This is to prevent the discharge pressure from being lost.

(Embodiment 6)
In the first embodiment, the mode in which one ink inlet channel is connected to one ink chamber has been described. In the sixth embodiment, a mode in which two or more ink inlet channels are connected to one ink chamber will be described.

  FIG. 11 is a partially enlarged plan view of the inkjet head 600 according to the sixth embodiment. FIG. 11 illustrates a state where the piezo plate 140 is removed. The inkjet head 600 is the same as the inkjet head 100 of Embodiment 1 shown in FIG. 4C except that it has a plurality of ink inlet holes 621 and a plurality of ink inlet channels 623. The same components as those of the ink jet head 100 of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 11, in the ink jet head 600 of the present embodiment, three ink inlet channels 623 are connected to one ink chamber 110. The ink inlet channels 623 at both ends are connected to corner portions of the ink chamber 110. By doing so, ink and bubbles are less likely to stay in the corner portion of the ink chamber 110. Therefore, according to the present embodiment, the ink ejection force can be further improved.

  In order to prevent ink and bubbles from staying in the corners of the ink chamber 110, instead of increasing the number of ink inlet channels 623, the width of one ink inlet channel 623 is made the same as the width of the ink chamber 110. It is also possible to do. However, from the viewpoint of preventing the discharge pressure from being lost, it is not preferable to make the width of the ink inlet channel 623 the same as the width of the ink chamber 110.

  In the ink jet head of the present invention, ink is stagnant in the ink chamber and the ink ejection force is strong. For this reason, the inkjet head of this invention can apply | coat a highly viscous ink stably to a to-be-coated article. Therefore, the ink jet head of the present invention is preferably used as an ink jet head for coating and forming an organic light emitting material in the manufacture of an organic EL display panel, for example.

100, 200, 300, 400, 500, 600 Inkjet head 101 Ink supply flow path 102 Ink discharge flow path 103 Ink introduction port 104 Ink discharge port 105 Ink tank 110 Ink chamber 111 Nozzle 112 Ejection hole 113 Laminated piezo element 121, 521, 621 Ink inlet hole 123, 223, 523, 623 Ink inlet channel 125 Ink outlet hole 127, 227 Ink outlet channel 130 Nozzle plate 140 Piezo plate 150 Partition 160 Frame 310 Tapered portion 410 Convex portion

Claims (4)

An ink chamber;
An ink supply channel through which ink for supplying to the ink chamber flows;
An ink discharge channel through which the ink discharged from the ink chamber flows;
A partition wall constituting the side surface of the ink chamber;
An ink inlet hole formed in the partition wall and in communication with the ink supply channel;
An ink outlet hole formed in the partition wall and in communication with the ink discharge channel;
A piezo plate constituting the top of the ink chamber;
A laminated piezo element which is disposed in the ink chamber and is extendable and contractible, the laminated piezo element having a fixed end fixed to the piezo plate, and a movable end which is an end portion in an extendable direction;
A nozzle plate constituting the bottom surface of the ink chamber;
An inkjet head having a nozzle formed on the nozzle plate and communicating with the ink chamber;
The laminated piezoelectric element is spaced apart from the partition;
The ink jet head, wherein the ink inlet hole is positioned on the fixed end side with respect to the movable end of the laminated piezoelectric element. An ink inlet channel connecting the ink inlet hole and the ink supply channel;
The inkjet head according to claim 1, wherein the ink inlet channel has a bending point. An ink outlet channel connecting the ink outlet hole and the ink discharge channel;
The inkjet head according to claim 1, wherein the ink outlet channel has a bending point. An ink jet apparatus comprising the ink jet head according to claim 1.

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